The present invention is directed toward a method and apparatus for the stabilization of pelvic fractures, particularly unstable fractures such as those referred to as Malgaigne fractures which involve fractures or dislocations of both the ilium or sacroiliac joint and the pubis or pubic symphysis. These fractures are vertically oriented and completely disrupt the integrity of the pelvic ring, thus permitting one-half of the pelvis to move in relation to the opposite half. Examples of these fractures include fracture of both the inferior and superior pubic ramus coupled with an ipsilateral sacroiliac dislocation; dislocation of the pubic symphysis in conjunction with a sacroiliac dislocation; and symphyseal dislocation with fracture of the ilium.
Stabilization of such fractures requires restoring the internal integrity anteriorly at the symphysis pubis and posteriorly across the ilium or the sacroiliac joint. Prior methods of posterior stabilization have involved the use of screws across the sacroiliac joint into the sacrum directly, a plate which bridges between the two iliac bones at the level of the posterior superior iliac spine and Harrington compression rods which traverse the iliac wings.
Although effective in certain instances, each of these prior methods and apparatus have distinct limitations and disadvantages.
In the case of sacral screws, that is screws passing directly from the ilium to the sacrum across the sacroiliac joint, the blind passage of these screws can damage structures in the sacrum or, if the sacrum is missed, the screws can damage the viscera in the pelvic brim. Furthermore, if the sacrum itself is fractured, it is difficult to get the correct screw length, again due to it being a blind passage.
The disadvantage of plate fixation is two fold; the variation in pelvic sizes requires several different sizes of plates, and, even when the correct size is used, the plates tend to hold the pelvic bones apart, that is in distraction, which does not promote bone healing but may cause a non-union to develop. In contrast to the plate, Harrington compression rods squeeze the fracture together which does promote healing; but they may cause the fracture to open anteriorly because there is no fixed relationship between the rod and the washer which actually compresses the fractures. This problem occurs in the transverse plane when compression is applied posteriorly causing the anterior of the symphysis pubis to open. In the coronal plane, since there is no fixation between the rod and the washer, a condition known as toggle can develop allowing one side of the pelvis to ride up and down relative to the opposite side.
Accordingly, it is an object of this invention to provide a method and apparatus for the stabilization of pelvic fractures that overcomes the disadvantages of the prior methods and apparatus. It is a further object to provide a further method and apparatus for the stabilization of pelvic fractures that provides rigid posterior fixation while maintaining anterior flexibility. It is a still further object to provide a method and apparatus for the stabilization of pelvic fractures that provides for rigid, non-wobbling posterior fixation.